1. Field of the Invention
The invention generally relates to an electronic apparatus, and more particularly to, a phase detecting apparatus and a phase adjusting method.
2. Description of Related Art
At a receiving end of high-speed serial data, in order to obtain the data accurately, a clock signal must be used as a basis for sampling the data, and a frequency and a phase of the clock signal must be locked on the received data signal. A traditional receiving end uses a clock data recovery device to provide the said clock signal.
A traditional clock data recovery device uses a voltage control oscillator (VCO) to provide the clock signal, samples the data signal with a phase detector according to the clock signal, and controls the charging and discharging of a charge pump according to a sampling value, so as to control the voltage control oscillator in adjusting the frequency of the clock signal, and thereby enables the clock signal to have a correct phase.
A conventional phase detector may determine whether the phase of the clock signal is being ahead or failing behind according to two adjacent data sampling values and a sampling value ranged between the edges of the two adjacent data sampling values, so as to accordingly control the charging and discharging of the charge pump and to timely adjust the phase of the clock signal. However, with the popularity and advances in communication technology, data transmission bit rate becomes higher and higher and signal attenuation becomes increasingly obvious, the conventional phase adjustment has gradually lost its adjustment precision, and thus a more accurate phase adjustment is in need for preventing circuit instability and circuit performance degradation from being caused due to phase difference.